Implantable stimulation devices deliver electrical stimuli to nerves and tissues for the therapy of various biological disorders, such as pacemakers to treat cardiac arrhythmia, defibrillators to treat cardiac fibrillation, cochlear stimulators to treat deafness, retinal stimulators to treat blindness, muscle stimulators to produce coordinated limb movement, spinal cord stimulators to treat chronic pain, cortical and Deep Brain Stimulators (DBS) to treat motor and psychological disorders, and other neural stimulators to treat urinary incontinence, sleep apnea, shoulder subluxation, etc. The description that follows will generally focus on the use of the invention within a Spinal Cord Stimulation (SCS) system, such as that disclosed in U.S. Pat. 6,516,227. However, the present invention may find applicability with any Implantable Medical Device (IMD) or in any IMD system.
An SCS system typically includes an Implantable Pulse Generator (IPG) 10 shown in plan and cross-sectional views in FIGS. 1A and 1B. The IMD 10 (more generally IMD 10) includes a biocompatible device case 30 that holds the circuitry and battery 36 (FIG. 1B) necessary for the IPG to function. The IMD 10 is coupled to electrodes 16 via one or more electrode leads 14 that form an electrode array 12. The electrodes 16 are configured to contact a patient's tissue and are carried on a flexible body 18, which also houses the individual lead wires 20 coupled to each electrode 16. The lead wires 20 are also coupled to proximal contacts 22, which are insertable into lead connectors 24 fixed in and encompassed by a header 28 on the IMD 10, which header can comprise an epoxy for example. Once inserted, the proximal contacts 22 connect to header contacts 26 in the lead connectors 24, which are in turn coupled by electrode feedthrough pins 34 through an electrode feedthrough 32 to circuitry within the case 30 (connection not shown). Case 30 can be formed of case portions 30a and 30b (FIG. 1B) which are laser welded together and to the electrode feedthrough 32.
In the illustrated IMD 10, there are thirty-two lead electrodes (E1-E32) split between four leads 14, with the header 28 containing a 2×2 array of lead connectors 24 to receive the leads' proximal ends. However, the number of leads and electrodes in an IPG is application specific and therefore can vary. In a SCS application, the electrode leads 14 are typically implanted proximate to the dura in a patient's spinal cord, and when a four-lead IMD 10 is used, these leads can be split with two on each of the right and left sides of the dura. The proximal electrodes 22 are tunneled through the patient's tissue to a distant location such as the buttocks where the IPG case 30 is implanted, at which point they are coupled to the lead connectors 24. A four-lead IMD 10 can also be used for Deep Brain Stimulation (DBS) in another example. In other IPG examples designed for implantation directly at a site requiring stimulation, the IPG can be lead-less, having electrodes 16 instead carried by the case of the IPG for contacting the patient's tissue.
As shown in the cross section of FIG. 1B, the IMD 10 includes a printed circuit board (PCB) 40. Electrically coupled to the PCB 40 are the battery 36, which in this example is rechargeable; other circuitry 46 coupled to top and/or bottom surfaces of the PCB, including a microcontroller and other circuitry necessary for IMD operation; a telemetry antenna—42a and/or 42b—for wirelessly communicating with an external device (FIGS. 2A and 2B); a charging coil 44 for wirelessly receiving a magnetic charging field from an external charger (not shown) for recharging the battery 36; and the electrode feedthrough pins 34 (connection to circuitry not shown). If battery 36 is permanent and not rechargeable, charging coil 44 would be unnecessary.
Both of telemetry antennas 42a and 42b can be used to transcutaneously communicate data through the patient's tissue to an external device, but are different in shape and in the electromagnetic fields they employ. Telemetry antenna 42a comprises a coil, which can bi-directionally communicate with an external device via a magnetic induction communication link, which comprises a magnetic field of typically less than 10 MHz operable in its near-field to communicate at a distance of 12 inches or less for example. Circuitry 46 would include telemetry circuitry coupled to the coil antenna 42a, including driver circuitry for energizing the coil antenna 42a to transmit data and receiver circuitry for resolving data received at the coil 42a. Such telemetry circuitry also operates in accordance with a modulation scheme (defining how data to be transmitted is modulated, and will be demodulated when received) and a communication protocol (defining the manner in which the data is formatted). A typical modulation scheme used for magnetic induction communications via coil antenna 42a is Frequency Shift Keying (FSK), although other modulation schemes could also be used.
Telemetry antenna 42b comprises a short-range Radio-Frequency (RF) antenna that operates in accordance with a short-range RF communication standard and its underlying modulation scheme and protocol to bi-directionally communicate with an external device along a short-range RF communication link. Short-range RF communication link typically operates using far-field electromagnetic waves ranging from 10 MHz to 10 GHz or so, and allows communications between devices at distances of about 50 feet or less. Short-range RF standards operable with antenna 42b include, for example, Bluetooth, BLE, NFC, Zigbee, WiFi (802.11x), and the Medical Implant Communication Service or the Medical Device Radiocommunications Service (both collectively referred to herein as “MICS” for short). Short-range RF antenna 42b can take any number of well-known forms for an electromagnetic antenna, such as patches, slots, wires, etc., and can operate as a dipole or a monopole. Circuitry 46 would include telemetry circuitry coupled to the short-range RF antenna 42b, again including driver and receiver circuitry.
IMD 10 could contain both the coil antenna 42a and the short-range RF antenna 42b to broaden the types of external devices with which the IMD 10 can communicate, although IMD 10 may also include only one of antenna 42a and 42b. 
Examples of different external devices operable to communicate with the IMD 10 are shown in FIGS. 2A and 2B. Such external devices are typically used to adjust the therapy settings the IMD 10 will provide to the patient—such as which electrodes 16 are active to issue pulses; whether such electrodes sink or source current (i.e., polarity); the duration, frequency, and amplitude of pulses, etc.—which settings together comprise a stimulation program for the patient. External devices can also act as receivers of data from the IMD 10, such as various data reporting on the IMD's status and the level of the IMD's battery 36.
An external device having such functionality is shown first in FIG. 2A in the form of a patient remote control 50. Remote control (RC) 50 is typically hand-held, portable, and powered by a battery (not shown) within the RC's housing 51, which battery may be a primary battery or rechargeable. The RC 50 includes a Graphical User Interface (GUI) 53 similar to that used for a cell phone, including buttons 52 and a screen 54, and may have other user interface aspects as well, such as a speaker. The RC 50 also includes within its housing 51 communication means, including a coil antenna 59a and/or a short-range RF antenna 59b, which are respectively compatible with a coil antenna 42a or a short-range RF antenna 42b usable in the IMD 10. Similar to the IMD 10, RC 50 can have either or both of the antennas 59a and 59b. Processing in the RC 50 is controlled via a microcontroller 56, which would couple to telemetry circuitry coupled to either or both of the antennas 59a and 59b. 
Shown on the screen 54 in FIG. 2A are various options provided by the GUI 53 and selectable by a patient to control his IMD 10 (e.g. the stimulation program it is executing) or to monitor his IMD 10. Just a few typical options are depicted for simplicity that enable the patient to: start or stop stimulation; increase or decrease the amplitude of the stimulation pulses; check IMD monitoring information, such as the battery 36 level, operating status of the IMD, or other data telemetered from the IMD; etc.
External devices such as the RC 50 of FIG. 2A were historically built by the manufacturers of IMDs, and thus were generally dedicated to communicate only with such IMDs. As such, dedicated RC 50 is not freely programmable by a patient, but is instead limited to the IMD functionality provided by the manufacturer, which may be updated from time to time. However, there are many user-programmable commercial mobile devices, such as cell phones, that can provide GUIs and have inherent communication means suitable for functioning as a wireless external controller for an IMD.
FIG. 2B show an example of a mobile device 60 configured for use as an external controller for an IMD, as described in commonly-owned U.S. Patent Application Publication 2015/0073498. The mobile device 60 may be a commercial, multipurpose, consumer device, such as a cell phone, tablet, personal data assistant, laptop or notebook computer, or like device—essentially any mobile, hand-holdable device capable of functioning as a wireless external controller for an IMD. Examples include the Apple iPhone or iPad, Microsoft Surface, Nokia Lumia devices, Samsung Galaxy devices, and Google Android devices for example.
As shown in FIG. 2B, the mobile device 60 includes a GUI 63 with a screen 64, which may also receive input if it is a touch screen. The mobile device 60 may also have buttons 62 (e.g., a keyboard) for receiving input from the patient, a speaker 66, and a microphone 68. Mobile device 60 further includes a battery (not shown) within its housing 61, which battery may be a primary battery or rechargeable. Mobile device 60 further includes at least one short-range RF antenna 69, and would include telemetry circuitry compliant with a short-range RF standard, such as Bluetooth in one example. Thus, mobile device 60 can inherently communicate via a short-range RF far-field link with an IMD having a short-range RF antenna 42b, assuming it is compliant with the Bluetooth standard. Mobile device 60 however is unlikely to contain a coil antenna similar to the coil antenna 59a of the RC 50 of FIG. 2B, and thus would be incapable by itself to communicate via a near-field magnetic inductive link with an IMD 10 having only a coil antenna 42a. (Mobile device 60 though could be used with other devices or accessories to enable communications with an IMD having a magnetic induction communication coil. See, e.g., U.S. Pat. Nos. 8,983,615 and 9,533,162; U.S. Patent Application Publications 2015/0231402 and 2016/0274752. Mobile device 60 may, in addition to short-range RF communication means enabled by antenna 69, further include longer-range cellular communication means as is well known.
Shown on the screen 64 is a Medical Device Application (MDA) 65, which may reside as microcode in the mobile device 60's microcontroller 67 or which may otherwise be stored in the mobile device's memory. When MDA 65 is executed by the patient (typically by selecting its icon, as explained in the '498 Publication), the microcontroller 67 will configure the mobile device 60 for use as an external controller to communicate with the IMD 10. The MDA 65 includes options selectable by a patient to control his stimulation program or monitor his IMD, similar to what was described earlier with respect to the GUI 53 of the dedicated RC 50 of FIG. 2A. The MDA 65, like other applications executable in the mobile device 60, may have been downloaded using traditional techniques, such as from an Internet server or an “app store.” Although not strictly necessary, MDA 65 is logically developed and provided by the manufacturer of the IMD, and may be made available in different versions to work with different mobile device operating systems (e.g., iOS, Android, Windows, etc.).
Both the RC 50 of FIG. 2A and the mobile device 60 of FIG. 2B can thus operate to communicate with an IMD 10 using short-range RF communication means, such as Bluetooth, if the IMD 10 includes a compliant short-range RF antenna 42b. However, the inventor perceives problems with this approach, particularly as concerns the IMD 10. In FIG. 1B, the short-range RF antenna 42b is included within the IMD's case 30. The case 30 is normally conductive and thus will attenuate wireless communications. This is particularly true if the short-range RF communication standard employs a relatively high frequency such as Bluetooth (e.g., 2.4 GHz). Attenuation using short-range RF communications is further exacerbated by the patient's tissue, although such effects can be mitigated if the IMD 10 is implanted shallowly in the patient and thus nearer to the patient's skin.
A manner of mitigating attenuation would be to include the short-range RF antenna 42b in the IMD's header 28. While a short-range RF antenna located in the header 28 would still suffer attenuation of communications related to the patient's tissue, the header material itself would not attenuate as it is formed of non-conductive epoxy. However, it is not a simple matter to put a short-range RF antenna in the IMD's header 28, as the header 28 typically includes very little free space. This is particularly true in an IMD 10 such as that depicted in FIG. 1A, which includes four lead connectors 24. Further, the lead connectors 24 are formed of conductive components (such as header contacts 26 and electrode feedthrough pins 34) which could interfere with communications of a header-based antenna.
The inventor thus proposes a different solution that provides an IMD 10 with a short-range RF antenna such as a Bluetooth antenna which is not significantly attenuated by materials of the IMD 10 itself, but which is not located in the IMD's header.